just wait and see

Occasionally things in this world don’t make sense. We all have a self-created model of how things in this world should work and if something reacts differently to what our model describes we are forced to ask ourselves why (Or Ignore or Worship, but that is something completely different).

A model I rely on is evolution, I believe that everything in the biological world should be explainable in terms of making an individual’s genes “fitter”, within the boundaries of gene mutation.

Normally this model is solid, but I did find something that doesn’t fit. I mean it probably does have an explanation but it is beyond me what it could be..

The anomaly is the phrenic nerve.

The phrenic nerve is what your brain uses to control your diaphragm, ie it controls your breathing. Normally nerves stay inside the spinal column for protection and the vertebra passes right through the diaphragm, it would make sense for the nerve to leave the spinal column right next to the muscle it controls right? This would mean it would only have to travel a few centimeters. But no, the phrenic nerve arises from the top of the neck and travels the length of your chest to the bottom of your ribs.

This is the reason a quadriplegic, who has no control over muscles below the severed spinal cord can still breath, because the nerve leaves the spine really early.

But it makes no sense for this to exist, there is no evolutionary advantage (As far as I can tell) and it exposes an important nerve.

So I’ve posted this question to an evolutionary forum, because according to my mental model this shouldn’t exist.

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Actually discrepancies between our mental models and the real world are good, they force a re-evaluation of the hypothesis.